1973 Volvo-Penta aq130c

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randyp

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I picked up a 1973 Glastron-Carlson with a AQ130C Volvo-Penta motor from a junk yard as a project. Had the motor rebuilt and after we started it, we found that the 2 middle cylinders aren't firing. The new plugs are sparking, both carb working properly, good compression in the cylinder, (125 psi+/-). Thought of a head gasket leak, but, no milky liquid or bubbles in the oil, and again, good compression. It has new distributor cap, points and rotor, and new coil. Thought the two lobes on the cam might be worn down in those cylinders, but lifters appear to be working as well as the other 2 cylinders.
Any help or suggestions would be greatly appreciated!!!!
Thanks, Randy
 

calwldlif

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Re: 1973 Volvo-Penta aq130c

lets see comp ok
plugs firing ok
fuel getting to cyl? plugs wet?
Is the exhaust mani clear on those cyls?
 

randyp

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Re: 1973 Volvo-Penta aq130c

I'll check manifold. Tried plug wires both ways, no change.
 

Starflight

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Re: 1973 Volvo-Penta aq130c

randyp said:
I picked up a 1973 Glastron-Carlson with a AQ130C Volvo-Penta motor from a junk yard as a project. Had the motor rebuilt and after we started it, we found that the 2 middle cylinders aren't firing. The new plugs are sparking, both carb working properly, good compression in the cylinder, (125 psi+/-). Thought of a head gasket leak, but, no milky liquid or bubbles in the oil, and again, good compression. It has new distributor cap, points and rotor, and new coil. Thought the two lobes on the cam might be worn down in those cylinders, but lifters appear to be working as well as the other 2 cylinders.
Any help or suggestions would be greatly appreciated!!!!
Thanks, Randy
 

Starflight

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Re: 1973 Volvo-Penta aq130c

The specs on my 75 aq130c is compression 170 -200 psi. I think your compression is low.
 

supercab78

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Re: 1973 Volvo-Penta aq130c

Just a thought; I've seen cars have a dead cylinder especialy at idle speed due to a open vacum line that goes into a port runner being off the intake. If a vacum line shares two manifold runners it may kill the two cylinders.
 

randyp

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Re: 1973 Volvo-Penta aq130c

I re-tested the compression, 140-145 in all 4 cyl's.
I don't see any vac. lines.
I heard that boats drop 2 cyl's when in reverse. Is that true with inboard engines, and could the problem lie with the shifter or linkage?
THANKS!!
 

Dunaruna

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Re: 1973 Volvo-Penta aq130c

[colour=blue]No, should not drop 2 cylinders in reverse.

Your comps have gone from 125+/- to 140-145.

We are not getting the full picture.

How do you know it's dropping the middle pots?
 

randyp

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Re: 1973 Volvo-Penta aq130c

When I tested the comp last week, it was 145. The guy that tested it before, let the guage go to about 125 and said that I had good comp. Not being a "motor guy" myself, I assumed he was correct.
When I pull the plugs from the 2 middle cyl's. they are clean, wet, and smell of fuel, but, there is no evidence of firing, and the 2 outside cyl's are brown with residue. When you pull the plug and turn the key, you see a blue spark in the plug. When the plug is reinserted, and the wire is pulled, you can hear the spark when held close to the plug, (and feel the shock!).
Could there be enough of a head gasket leak to foul out the inner cyl's., but not be severe enough to see water in the oil?
 

Starflight

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Re: 1973 Volvo-Penta aq130c

randyp said:
When I tested the comp last week, it was 145. The guy that tested it before, let the guage go to about 125 and said that I had good comp. Not being a "motor guy" myself, I assumed he was correct.
When I pull the plugs from the 2 middle cyl's. they are clean, wet, and smell of fuel, but, there is no evidence of firing, and the 2 outside cyl's are brown with residue. When you pull the plug and turn the key, you see a blue spark in the plug. When the plug is reinserted, and the wire is pulled, you can hear the spark when held close to the plug, (and feel the shock!).
Could there be enough of a head gasket leak to foul out the inner cyl's., but not be severe enough to see water in the oil?

These are my thoughts..... On a fresh rebuild, the compression should be at spec.(170-200#s) my1975 aq130c w/120 hrs(no rebuild yet) has 175-190#s. the compression ratio is 9.5:1 the aq130b has a comp.ratio 8.4:1 w/ comp. spec of 145-170#s. Are you sure you dont have the aq130b? the only differance I see between the 2 are the head gaskets. all the other parts are the same. i.e. pistons, rods, heads, block. With that being said, I would have to ask why your compression is so low? Wrong head gasket? Valve lash not correct? The valve lash should be 0.020-0.022 warm or cold engine. If the valve lash is too tight, the valves will leak (not seat properly), and will cause low compression. Will also cause mis-fire, and should backfire through the carb. If you had a blown head gasket( fresh rebuild, it shouldnt be a problem), the leaking cylinder or cylinders would have alot less compression than the others. if the blown gasket was miniscule, and had a little compression loss, it should still fire. if water was leaking into the cylinder, it should be evident. You should see water beading on the plug you pulled if enough were getting in to keep the plug from firing.
Answer these questions and myself or others will be able to help you further.
 

ss16 carlson

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Re: 1973 Volvo-Penta aq130c

hello everyone, I just bought my first restore project.16 cv/ss glastron/carlson. I wont have it home until saturday. post pictures then. can't wait to start. Its go a 130 volvo pinta. omc outdrive.:D any web sites that can help with restore would be great.
 

ChristianLemay

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Jul 21, 2023
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I just changed the rings on my AQ130C but I cannot see the specifications for the connecting rod tightening torque. My manueal does not give any info ont the tightening Torques on connecting rod. Any idea?
 
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